Wireless telegraphy and telephony

ABSTRACT

190,699. Ges. f³r Drahtlose Telegraphie. Dec. 20, 1921, [Convention date]. Thermionic amplifiers, oscillation-generators and modulating systems; diplex signalling.-In order to permit of transmission and reception on the same carrier wave length in a high-frequency telephony system, the thermionic generator of the carrier wave is interrupted at super-audible frequency. During the periods of self-oscillation, the tube is used for transmission, whilst it acts as a receiver during the intervals of interruption or non-oscillation. In a two-grid generator, the space-charge grid 8 is connected to an ohmic resistance 9 in the anode circuit of a second valve 10 energized by an oscillator 12, so that an alternating potential is imposed upon the grid 8. During periods of high potential, carrier-wave oscillations are created in the anode circuit 2, 3 and may be modulated by a microphone 6. When the charge on the grid 8 is relatively negative, the tube 4 does not generate, but acts as a receiver of incoming signals from the circuit 1. Any form of thermionic generator may be used in place of the two-grid form shown.

June 26, 1928. 1,674,784 M. LOCK WIRELESS TELEGRAPHY AND TELEPHONY Filed Dec. 5. 1922 W VOLTAG c m T! M E avwawtoz EL LOCK Patented June 26, 1928.

UNITED" STATES PATENT OFFICE.

MICHAEL LOOK, OF BERLIN, GERMANY, ASSIGNOR T GESELLBCKAIT m DRAHTLOSE TELEGRAPHIE I. B. H. HALLESCHES, OF BERLIN, GERMANY, A CORPORATION OF GERMANY.

WIRELESS TELEGRAPHY AND TELEPHONY.

Application filed December 5, 1922, Serial No. 604,999, and in Germany December 20, 1981.

In wireless communication and particularly in wireless telephony in order to make possible simultaneous transmission and reception without switching operations, it has heretofore been proposed to select waves of two different frequencies for a connection.

For example, it has been proposed to opcrate the sender of one station at a carrier frequency a to which the receiver of the other station is tuned, and to operate the sender of the latter station at a different carrier frequency b to which the receiver of the first-mentioned station is tuned. In this manner transmission and reception may be efi'ected at two independent carrier frequencies whereby communication in opposite directions is po=sible.

In view of the fact that for a certain number of conversations only a limited number of wave lengths are at dis osal, the use of two wave lengths fora c iier'sation' constitutes always a poor utilization of the given number of wave lengths.- It is impossible to have the two wave lengths necessary for a conversation very near each other because in that case the receiver will be considerably influenced by its associated sender whereby the sensitiveness of the receiver will be reduced.

An object of the invention to be hereinafter set forth is to make possible conversation in opposite directions by means of a single wave length. To this end, a tube arran ement is used which serves for both sen ing and receiving and which, through the agencyof special means, is alternately operated exclusively as a sender or as a receiver.- This alternation in the operation of the tube arrangement as a sender and as a receiver occurs so quickly that it is not audible and will not alter the character of speech in telephony.

In the drawing- Fig. 1 is a diagrammatic representation of a circuit arrangement embodying the invention, and

Fig. 2 is a graphic illustration of the changes in. potential impressed upon the second grid of the main vacuum tube.

In the illustrated arrangement, 1 is an antenna circuit, and 2 is a coil which together with condenser 3 constitutes an oscillating' circuit. In the well known manner this circuit is energized by undamped oscillations generated by the tube 4. The conductor leading to the controlling grid 5 includes a. telephone transmitter 6 and the anode circuit includes a receiver 7. The tube may, for instance, have two grids and its second space charging grid 8 may be connected with an ohmic resistance 9 provided in the anode circuit of a cathode tube 10. The grid 11 of cathode tube 10 has an alternating potential impressed on it by the small aux1liary oscillator 12. The frequency of this potential will determine the timing of the alternation in the operation of the tube 4 as a sending and as a receiving tube.-

This is attained by the production in the well known manner shown in Fig. -2, in which 10 denotes otential and t time, of a potential at the o mic resistance andtherefore at the space char -ng grid 8 of the tube 4. This otential on t e space charging grid 8 contro s the anode current in the tube 4, i. e. it decreases thelatter for a definite period of time and then permits it to rise again. When the anode current is small, the tube 4 will cease to oscillate and operates as a receiver. When this current is large, the

tube 0 crates as a sender. This makes possible t e alternate operation of the arrangement as a sender and as a receiver.

It is not necemary that a: circuit arrangement of the particular type shown in 1 be used. Any vacuum tube or amplifying arrangement may be employed, which is the equivalent of the last-mentioned arrangement. So long as the tube circuit effects the generation of the carrier frequency, the character of the arrangement is immaterial from the standpoint of the invention. r

Having described my invention I declare that what I claim is 1. In a signalling system using radio frequency, a thermionic tube having at least three electrodes, means for causing the tube to produce oscillations to enable it to be operated as an oscillator, and for intermittently decreasing the current in the anode circuit of the tube to cause it to cease to function as an oscillator and to function'as a detector, said means operating at an inaudible frequency.

7 2. In a signalling system using radio frequency, a thermionlc tube having a cathode, anode, and grid, the anode circuit and grid circuit being regeneratively coupled, a

fourth electrode in said tube, means for impressin a changin potential on said fourth electr e so as to a ternately cause said tube to function as an oscillator and as a detector, the frequency of the alternations being in audible.

3. In a signalling system using radio freuency, a thermionic tube having at least t ree electrodes, the grid and plate circuits being regeneratively coupled, telephone receiving means in said plate circuit, telephone transmitting means in said grid circuit, and means for intermittently decreasing the plate current of the tube so as to prevent functioning of the tube as transmitter and to cause it to function as a detector, said last mentioned means operating at an inaudible frequency.

4. In a signalling system using radio frequency, a vacuum tube. means whereby thevacuum tube may function as a generator of oscillations or as a detector. and additional means for alternately and automatically causing said vacuum tube to function as a generator and as a detector.

5. In a signalling system using radio frequency, a vacuum tube, means whereby the vacuum tube may function as a generator of oscillations or as a detector of oscillations,

and additional means for alternately causing said vacuum tube to function as a generator and as a detector, the frequency of the alternations being inaudible.

6. In a signalling system using radio frequency, a thermionic tube, means whereby said tube may function as an oscillator for sending or as a detector for receiving, and additional means for alternately causing said tube to function as an oscillator and as a detector, the frequency of the alternations being above audibility.

7. In a signalling system using radio frequency, a thermionic tube having a cathode, anode and grid, means for alternately causing the tube to produce oscillations for sending and causing the tube not to oscillate for receiving, said means operating at an inaudible frequency, and comprising a fourth electrode in the tube, a thermionic tube amplifier connected to the fourth electrode, and a master oscillator feeding said amplifier.

8. In a signalling system using radio frequency, a thermionic tube having a cathode, anode and grid, means for causing said tube to produce oscillations, and means for intermittently decreasing the anode current of the tube to cause it to cease to function as an oscillator and simultaneously to cause it to function as a detector, said means operating at inaudible frequency and comprising a thermionic tube amplifier having an ohmic resistance in its anode circuit, a fourth electrode in the first-mentioned tube connected to the anode circuit of the amplifier between said resistance and the anode of the amplifier, and a master oscillator coupled to the grid-filament circuit of the amplifier for causing it to impress changing potentials on said fourth electrode.

9. In a signalling system using radio frequency, a thermionic tube having a cathode, anode, and grid, the anode circuit and grid circuit being regeneratively coupled,. a fourth electrode in said tube, means for impressing a changing potential on said fourth elect-rode so as to alternately cause said tube to function as an oscillator and as a detector.

MICHAEL LOCK. 

